Initial library structure, build system and packet implementation
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324
src/packet.zig
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324
src/packet.zig
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///////////////// Imports
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//
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const std = @import("std");
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///////////////// Constants
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//
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const expect = std.testing.expect;
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const memeql = std.mem.eql;
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const asBytes = std.mem.asBytes;
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const MAX_DATA_SIZE = 465;
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const ADDRESS_SIZE = 16;
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///////////////// Enums
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//
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const IfacFlag = enum(u1) {
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open = 0, // Packet for publically accessible interface
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authenticated = 1, // Interface authentication is included in packet
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};
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const HeaderType = enum(u1) {
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type1 = 0, // One address field
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type2 = 1, // Two address fields
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};
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const ContextFlag = enum(u1) { // Meaning depends on packet context
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unset = 0,
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set = 1,
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};
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const PropagationType = enum(u1) { broadcast = 0, transport = 1 };
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const DestinationType = enum(u2) { //
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single = 0b0,
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group = 0b01,
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plain = 0b10,
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link = 0b11,
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};
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const PacketType = enum(u2) { //
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data = 0b0,
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announce = 0b01,
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link_request = 0b10,
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proof = 0b11,
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};
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const PacketContext = enum(u8) {
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none = 0x00, // Generic data packet
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resource = 0x01, // Packet is part of a resource
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resource_adv = 0x02, // Packet is a resource advertisement
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resource_req = 0x03, // Packet is a resource part request
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resource_hmu = 0x04, // Packet is a resource hashmap update
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resource_prf = 0x05, // Packet is a resource proof
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resource_icl = 0x06, // Packet is a resource initiator cancel message
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resource_rcl = 0x07, // Packet is a resource receiver cancel message
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cache_request = 0x08, // Packet is a cache request
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request = 0x09, // Packet is a request
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response = 0x0A, // Packet is a response to a request
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path_response = 0x0B, // Packet is a response to a path request
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command = 0x0C, // Packet is a command
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command_status = 0x0D, // Packet is a status of an executed command
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channel = 0x0E, // Packet contains link channel data
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keepalive = 0xFA, // Packet is a keepalive packet
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linkidentify = 0xFB, // Packet is a link peer identification proof
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linkclose = 0xFC, // Packet is a link close message
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linkproof = 0xFD, // Packet is a link packet proof
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lrrtt = 0xFE, // Packet is a link request round-trip time measurement
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lrproof = 0xFF, // Packet is a link request proof
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};
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///////////////// Structs
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//
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const PacketHeader = packed struct {
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ifac: IfacFlag,
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header: HeaderType,
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context: ContextFlag,
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propagation: PropagationType,
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destination: DestinationType,
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packet: PacketType,
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hops: u8, //
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};
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const Packet = struct {
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header: PacketHeader,
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address1: [ADDRESS_SIZE]u8,
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address2: [ADDRESS_SIZE]u8,
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context: PacketContext,
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data: []const u8, //
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};
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///////////////// Functions
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//
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pub fn serializePacket(packet: Packet, output_buffer: []u8) !usize {
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const has_two_addresses = packet.header.header == HeaderType.type2;
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// Compute size of final packet (in bytes)
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var target_size: u16 = @sizeOf(Packet);
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if (!has_two_addresses) {
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target_size -= packet.address2.len;
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}
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// TODO check data len
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if (output_buffer.len < target_size) {
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return error.BufferTooShort;
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}
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// Write buffer
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var offset: usize = 0;
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@memcpy(output_buffer[offset .. offset + @sizeOf(PacketHeader)], asBytes(&packet.header));
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offset += @sizeOf(PacketHeader);
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@memcpy(output_buffer[offset .. offset + ADDRESS_SIZE], asBytes(&packet.address1));
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offset += ADDRESS_SIZE;
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if (has_two_addresses) {
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@memcpy(output_buffer[offset .. offset + ADDRESS_SIZE], asBytes(&packet.address2));
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offset += ADDRESS_SIZE;
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}
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@memcpy(output_buffer[offset .. offset + @sizeOf(PacketContext)], asBytes(&packet.context));
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offset += @sizeOf(PacketContext);
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@memcpy(output_buffer[offset .. offset + packet.data.len], packet.data);
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offset += packet.data.len;
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if (target_size != offset) {
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return error.InternalError;
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}
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return offset;
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}
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fn copyToPacket(dst: anytype, src: []const u8, offset: usize, count: usize) !usize {
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if (src.len > offset + count) {
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return error.BufferTooShort;
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}
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@memcpy(@as(*u8, &dst), src[offset .. offset + count]);
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return offset + count;
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}
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// Reads the message buffer and builds the corresponding packet struct inside dest_packet
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pub fn deserializePacket(message_buffer: []u8, dest_packet: *Packet) !void {
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var offset: usize = 0;
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offset = try copyToPacket(&dest_packet.header, message_buffer, offset, @sizeOf(PacketHeader));
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offset = try copyToPacket(&dest_packet.address1, message_buffer, offset, ADDRESS_SIZE);
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const has_two_addresses = dest_packet.header.header == HeaderType.type2;
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if (has_two_addresses) {
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offset = try copyToPacket(&dest_packet.address2, message_buffer, offset, ADDRESS_SIZE);
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}
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offset = try copyToPacket(&dest_packet.context, message_buffer, offset, @sizeOf(PacketContext));
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// TODO compute data length
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const data_len = 0;
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offset = try copyToPacket(&dest_packet.data, message_buffer, offset, data_len);
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}
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///////////////// Tests
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//
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// Serializes the given packet and makes sure the output is correct
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fn testPacketSerialization(packet: Packet) !void {
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const buf_size = comptime @sizeOf(Packet) + MAX_DATA_SIZE;
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var buf: [buf_size]u8 = undefined;
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const res: usize = try serializePacket(packet, &buf);
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var expected_res: usize = @sizeOf(PacketHeader) + packet.address1.len + @sizeOf(PacketContext) + packet.data.len;
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const has_second_address = packet.header.header == HeaderType.type2;
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if (has_second_address) {
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expected_res += packet.address2.len;
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}
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try expect(res == expected_res);
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var offset: usize = 0;
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try expect(memeql(u8, buf[offset .. offset + @sizeOf(PacketHeader)], asBytes(&packet.header)));
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offset += @sizeOf(PacketHeader);
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try expect(memeql(u8, buf[offset .. offset + packet.address1.len], asBytes(&packet.address1)));
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offset += packet.address1.len;
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try expect(memeql(u8, buf[offset .. offset + @sizeOf(PacketContext)], asBytes(&packet.context)));
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offset += @sizeOf(PacketContext);
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try expect(memeql(u8, buf[offset .. offset + packet.data.len], packet.data));
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offset += packet.data.len;
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}
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test "Structs size" {
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try expect(@sizeOf(PacketHeader) == 2);
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}
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test "Basic serialization: header type 1, max data size" {
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const header: PacketHeader = .{
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.ifac = IfacFlag.open,
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.header = HeaderType.type1,
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.context = ContextFlag.set,
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.propagation = PropagationType.transport,
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.destination = DestinationType.single,
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.packet = PacketType.announce,
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.hops = 0,
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};
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const data_size = MAX_DATA_SIZE;
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const data: [data_size]u8 = undefined;
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const packet: Packet = .{ //
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.header = header,
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.address1 = undefined,
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.address2 = undefined,
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.context = PacketContext.none,
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.data = &data,
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};
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try testPacketSerialization(packet);
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}
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test "Basic serialization: header type 2, max data size" {
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const header: PacketHeader = .{
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.ifac = IfacFlag.open,
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.header = HeaderType.type2,
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.context = ContextFlag.set,
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.propagation = PropagationType.transport,
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.destination = DestinationType.single,
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.packet = PacketType.announce,
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.hops = 0,
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};
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const data_size = MAX_DATA_SIZE;
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const data: [data_size]u8 = undefined;
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const packet: Packet = .{ //
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.header = header,
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.address1 = undefined,
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.address2 = undefined,
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.context = PacketContext.none,
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.data = &data,
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};
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try testPacketSerialization(packet);
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}
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test "Basic serialization: header type 1, medium data size" {
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const header: PacketHeader = .{
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.ifac = IfacFlag.open,
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.header = HeaderType.type1,
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.context = ContextFlag.set,
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.propagation = PropagationType.transport,
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.destination = DestinationType.single,
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.packet = PacketType.announce,
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.hops = 0,
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};
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const data_size = MAX_DATA_SIZE / 2 + 3;
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const data: [data_size]u8 = undefined;
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const packet: Packet = .{ //
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.header = header,
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.address1 = undefined,
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.address2 = undefined,
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.context = PacketContext.none,
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.data = &data,
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};
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try testPacketSerialization(packet);
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}
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test "Basic serialization: header type 2, medium data size" {
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const header: PacketHeader = .{
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.ifac = IfacFlag.open,
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.header = HeaderType.type2,
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.context = ContextFlag.set,
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.propagation = PropagationType.transport,
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.destination = DestinationType.single,
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.packet = PacketType.announce,
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.hops = 0,
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};
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const data_size = MAX_DATA_SIZE / 2 + 3;
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const data: [data_size]u8 = undefined;
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const packet: Packet = .{ //
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.header = header,
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.address1 = undefined,
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.address2 = undefined,
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.context = PacketContext.none,
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.data = &data,
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};
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try testPacketSerialization(packet);
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}
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test "Serialize / Deserialize Packet: Header type2, Medium data size" {
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const header: PacketHeader = .{
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.ifac = IfacFlag.open,
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.header = HeaderType.type2,
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.context = ContextFlag.set,
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.propagation = PropagationType.transport,
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.destination = DestinationType.single,
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.packet = PacketType.announce,
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.hops = 0,
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};
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const data_size = MAX_DATA_SIZE / 2 + 3;
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const data: [data_size]u8 = undefined;
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const packet: Packet = .{ //
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.header = header,
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.address1 = undefined,
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.address2 = undefined,
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.context = PacketContext.none,
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.data = &data,
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};
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const buf_size = comptime @sizeOf(Packet) + MAX_DATA_SIZE;
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var buf: [buf_size]u8 = undefined;
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var res_packet: Packet = undefined;
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_ = try serializePacket(packet, &buf);
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try deserializePacket(&buf, &res_packet);
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try expect(res_packet == packet);
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}
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1
src/root.zig
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1
src/root.zig
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@ -0,0 +1 @@
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const packet = @import("packet.zig");
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